Internal combustion engine



E; M. TRAMMELL, JR

INTERNAL COMBUSTIONv ENGINE July 28, 1970 Filed Dec. 8, 1968 2 Sheets-Sheet 1 July 28, 1970 Filed Dec. 3, 1968 E. M. TRAMMELL, JR

INTERNAL COMBUSTION ENGINE 2 Sheets-Sheet 2 jvmsA/zoz [454 M mom/41., JF.

4342 Mar United States Patent 3,521,615 INTERNAL COMBUSTION ENGINE Earl M. Trammell, In, 39 Salem Estates Drive,

Ladue, Mo. 63124 Continuation-impart of applications Ser. No. 734,162 and Ser. No. 734,163, both filed June 3, 1968. This application Dec. 3, 1968, Ser. No. 780,697

Int. Cl. F021) 75/32; F16h 21/22 U.S. Cl. 123-197 14 Claims ABSTRACT OF THE DISCLOSURE A dual crankshaft assembly in an internal combustion engine that permits a substantial reduction in conventional connecting rod lengths for piston-operating engines. The assembly has a pair of crankshafts disposed on opposite sides of a piston. A piston-connecting means extends laterally outward from the piston base to opposite sides of the cylinder for operative attachment to a pair of connecting rods, one rod being operatively attached to one crankshaft and the other rod being operatively attached to the other crankshaft. The connecting rods have a length that is less than the stroke and greater than onehalf of the stroke.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending US. application Ser. No. 734,163, filed June 3, 1968 and US. application Ser. No. 734,162, filed June 3, 1968.

BACKGROUND OF THE INVENTION This invention relates generally to improvements in internal combustion engines, and more particularly to an improved dual crankshaft design that permits substantial reduction in connecting rod lengths. It is an improvement of US Pat. No. 3,386,429.

In heretofore conventional engines with average sixinch connecting rods and with three to four-inch strokes, maximum combustion pressures occur at approximately 20 past DTC (dead top center) of the power stroke. Maximum accelerated piston travel occurs, and piston thrust is transmitted into maximum torque at approximately 70 or more past DTC.

The crankshaft assembly in US. Pat. No. 3,386,429 and in co-pending application, Ser. No. 734,162, permits maximum reduction in effective connecting rod lengths so as to gain greater torque and engine efficiency. However, the crankshaft assembly in US. Pat. No. 3,386,429 uses a circular connector bearing, and the crankshaft in copending application, Ser. No. 734,162 uses a unitary connector bearing-crankarm bearing combination piece, rather than the conventional type of connecting rod.

In the past, a dual crankshaft assembly has been used to reduce cylinder wear and minimize side piston thrust, but in all instances, relatively long connecting rods have been utilized with all of the attendant disadvantages and restrictions regarding low torque, inefficient thermal energy transmittal to mechanical energy and large engine size.

SUMMARY OF THE INVENTION The present crankshaft assembly introduces a new combination engine structure for dual crankshaft engines that delivers greater torque and engine performance with greater economy. The assembly incorporates a new piston 3,521,615 Patented July 28, 1970 design in combination with novel connecting rods and dual crankshafts.

More specifically, the crankshaft assembly has a pair of crankshafts on opposite sides of the piston, the piston having a piston-connecting means extending laterally outward from opposite sides of the cylinder for pivotal attachment to.a pair of short connecting rods. One rod is oscillatively attached to one crankshaft, while the other rod is oscillatively attached to the other crankshaft. To achieve minimum practical rod length, the rods are confined to a length that is less than the engine stroke, but greater than one-half the stroke.

The piston-connecting means is carried by the piston base and is narrow so that the piston can travel downward and between the crankarrns during crankshaft rotation. Preferably, each rod is connected at a point on the pistonconnecting means which is located substantially between 10 on either side of a line passed through the center axes of the associated crank-arm bearing and crankshaft when the crankshaft is in dead top center. While a cylindrical piston has been disclosed, an oblong piston would have the same performance in conjunction with the other parts.

With this crank assembly, maximum piston speed occurs nearer maximum combustion pressure of the power stroke than on present day engines. This condition provides more eflicient transmittal of thermal energy into mechanical energy or power. It also permits the use of higher compression ratios.

The substantially shorter connecting rod, which directly controls or governs the moment of maximum piston speed, also becomes tangent to the crankarm travel nearer maxi mum combustion pressure of the power stroke than on present engines. This produces greater torque. To be specific, in present automobile engines, maximum combustion pressure occurs at around 20 past DTC, while maximum piston speed and maximum possible torque transmittal occur at approximately or more past DTC. With this improved engine structure, maximum piston speed and torque transmittal can be made to occur at a much earlier degree past DTC and therefore much closer to maximum combustion pressure. The present structure dimensions accomplish maximum piston speed and torque transmittal at approximately 53 past DTC. For this reason, with bore and stroke being equal, this new engine will develop greater torque and power over present engines.

The crank assembly permits the practical use of much larger engine bores and the building of high horsepower fourand six-cylinder, opposed engines with improved performance and gasoline economy. The use of these large bores is made possible by this improved dual transmission of piston forces that provides for greater engine strength and an inherently better balanced engine.

Greater engine compactness is accomplished by the use of substantially shorter connecting rods in combination with novel piston design. Although additional space is required to house the dual crankshaft, an opposed type engine incorporating this new structure will have a reduced width over current opposed type engines and will afford more efficient installation in an automobile.

The dual crankshaft assembly eliminates all piston side thrust against the cylinder walls. While this result is not an imperative improvement to current design engines, it is very important to the subject engine. To explain, at the moment this short connecting rod is transmitting an increased (compared to todays engines) amount of torque to the crankshaft, it is at the same time causing an equally opposite amount of piston side thrust against the cylinder wall. It is therefore very important to eliminate this severe piston side thrust and friction as is accomplished by this new engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical section through an internal combustion engine taken through one of the cylinders, the piston being illustrated at DTC (dead top center);

FIG. 2 is a side elevational view of FIG. 1, illustrating opposed cylinders with the crankshaft at 180 past DTC;

FIG. 3 is a bottom plan view of FIG. 1 with the crankshaft at 90 past DTC, and

FIG. 4 is a fragmentary view of the piston and one crankshaft illustrated at 90 before DTC.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now by characters of reference to the drawings, and first to FIG. 1, it will be understood that the internal combustion engine includes a block generally indicated by 10, having a cylinder 11 of substantially circular cross section. The top of the cylinder 11 is closed by a head 12 carrying the valves 13 and a sparkplug 14. The head 12 is shaped to form the combustion chamber 15. Reciprocatively mounted in the cylinder 11 is a compatible piston 16. As is best shown in FIG. 3, the piston 16 has a substantially circular configuration that closely matches the circular shape of cylinder 11.

Because of the crankshaft mechanism incorporated in this engine, there is no side thrust between the piston 16 and the walls defining the cylinder 11. Therefore, a piston 16 and cylinder 11, having an oblong configuration could be used.

For reasons which will later appear, the lateral walls of the cylinder 11 are cut away to provide lateral wall openings 17.

Formed integrally with the base of piston 16 and extending transversely through the lateral wall openings 17 is a piston-connecting means 20. The piston-connecting means 20 includes a bifurcated end 21 located outwardly of and at opposite sides of cylinder 11. Extending between each bifurcated end 21 is a wrist pin 22, the center axis of which is designated by the reference character A. The piston-connecting means 20 is relatively narrow.

Extending longitudinally in the engine block 10 are a pair of rotatively mounted crankshafts 23. The crankshafts 23 are laterally spaced and located on opposite sides of the piston 16 and cylinder 11. The center axis of each crankshaft 23 is designated by the reference character C. Each crankshaft 23 is of identical construction, so that a detailed description of one will sufiice for the other. For example, the crankshaft 23 includes a pair of longitudinally spaced crankarms 24 and a crankarm bearing 25 extending between the crankarms 24. The center axis of the crankarm bearing 25 is designated by reference character B. For reasons which will later appear, the crankarms 24 are spaced a distance slightly greater than the Width of the narrow piston-connecting means 20.

The crankshafts 23 are rotatively mounted in bearings 26 in the usual manner. Because dual crankshafts 23 are utilized, such crankshafts must be synchronized. Ac cordingly, a conventional way of synchronizing dual crankshafts is to operatively interconnect such crankshafts with interconnecting gearing, such as that represented by reference numeral 27 in FIG. 1.

Oscillatively mounted on the crankarm bearing 25 is a short connecting rod 30. The wrist pin 22 oscillatively mounts and connects the rod 30 to the piston 16. The distance between the center axis A of wrist pin 22 and the center axis B of the crankarm bearing 25 is the effective length of a connecting rod 30. The distance between the center axis B of crankarm bearing 25 and the center axis C of the crankshaft 23 represents the crankarm radius or throw. The distance between the center axes A and B is greater than the distance between the center axes B and C, yet less than twice the distance between the center axes B and C. Stated another way, the connecting rod 30 has a length that is less than the stroke and greater than one-half the stroke.

The crankarm bearing 25 has a reduced intermediate portion 31 on which the connecting rod 30 is rotatively mounted. The side shoulders (FIG. 3) of the reduced bearing portion 31 laterally engage the connecting rod 30 to preclude axial shifting during rotation of the crankshaft 23.

In the preferred embodiment, when the crankshaft 23 is located in DTC, the wrist pin 22 is located substantially between 10 on either side of a line passed through the center axes B and C of the associated crankarm bearing 25 and crankshaft 23 respectively. As shown in FIG. 1, a line passed between the center axes A and B is located at approximately 10 from the line passed through the center axes B and C.

The described dual crankshaft and piston-cylinder construction achieves the shortest possible connecting rod length using a conventional type of connecting rod with all of the resultant functional advantages.

It is thought that the functional advantages have become fully apparent from the foregoing detailed description of parts, but for completeness of disclosure, a brief description of the operation will be given.

The component parts of the dual crankshaft mechanism assume the positions illustrated in FIG. 1 when the piston 16 is located at DTC. As the piston moves downwardly in the cylinder 11, the crankarm bearing 25 of the right-hand crankshaft 23 rotates in a clockwise direction. Conversely, the crankarm bearing 25 of the left-hand crankshaft 23 rotates in a counterclockwise direction. The narrow piston-connecting means 20 attached to the bottom of piston 16 moves downwardly between the crankarms 24. The connecting rod 30 of the right-hand crankshaft 23 will turn about the crankarm bearing 22 and will turn freely in a relative counterclockwise direction on the wrist pin 22. The other connecting rod 30 of the left-hand crankshaft 23 will turn about its crankarm bearing 25 and will turn freely in a relative clockwise direction on its wrist pin 22. Upon continued downward movement of the piston 16, the crankshafts 23 will rotate and the crankarm bearings will move to past DTC, at which point, the connecting rods will have turned on their associated wrist pins 22 back to their initial position shown in FIG. 1. The 180 past DTC position is illustrated in FIG. 2.

As the piston 16 moves outwardly in the cylinder 11, the right-hand crankshaft 23 will continue to move in a clockwise direction and the left-hand crankshaft 23 will continue to move in a counterclockwise direction, thereby causing their associated connecting rods 30 to turn about the crankarm bearings 25 and wrist pins 22. The relative position of the right-hand crankshaft 23 and its associated connecting rod 30 at the 270 past -DTC is illustrated in FIG. 4. Upon continued rotation of the crankshafts 23, as the crankarm bearings 25 approach the DTC position shown in FIG. 1, the connecting rod 30 of the right-hand crankshaft 23 will turn in a counterclockwise direction on its wrist pin 22 back to its initial position shown in FIG. 1, while the connecting rod 30 of the left-hand crankshaft 23 will turn in a clockwise direction on its wrist pin 22 back to its initial position shown in FIG. 1. It will be understood that the connecting rods 30 will oscillate between limits on the crankarm bearings 25 and on the wrist pins 22. during each cycle of crankshaft rotation.

Maximum piston speed occurs and the piston thrust is transmitted into maximum torque at about 53 past DTC. In the heretofore conventional engines, maximum accelerated piston travel and piston thrust is transmitted into maximum torque at approximately 70 or more past DTC. Therefore it can be shown, strokes being equal, that the subject crankshaft mechanism will 'provide considerably faster piston speed and more torque from 1 to about 53 of the power stroke than that of the heretofore conventional engines. Obviously, with maximum combustion pressure occurring around 20 past DTC, it can be seen that this engine will attain greater efficiency and torque.

Again, it is pointed out, from 1 to about 53 past DTC, which in high compression engines is sufiicient range for expending effective pressures, that the shorter rod action made possible through the subject crankshaft mechanism will provide considerably more torque than that of heretofore conventional engines which are governed by considerably longer rods.

Moreover, because the dual crankshafts 23 are utilized, the side thrust forces by the piston 16 on the wall of cylinder 11 are substantially eliminated. Very short connecting rods would create considerable side thrust forces between the piston and cylinder if only a single crankshaft was utilized. However, because of the dual crankshaft mechanism, these side thrust forces are balanced. The fairly short connecting rod lengths provided by this engine are most practical in providing higher torque and faster piston speeds nearer maximum com'bustion pressure than that previously attained. Friction and wear is minimized to the greatest possible extent. Larger piston bores are made practical for fourand six-cylinder opposed type engines to provide improved performance and gasoline economy, and greater engine strength and balance. The use of substantially shorter connecting rods in combination with the novel piston design provides greater engine compactmess.

I claim as my invention:

1. In an internal combustion engine:

(a) a cylinder,

(b) a piston reciprocatively mounted in the cylinder,

the piston having piston-connecting means,

(c) a first crankshaft including a crankarm having a crankarm bearing,

(d) a first connecting rod operatively connecting the crankarm bearing to the piston-connecting means, and

(e) the connecting rod having a length that is less than twice the length of the crankarm, yet greater than the crankarm length.

2. An internal combustion engine as defined in claim 1, in which:

(f) the piston-connecting means extends laterally outward of the cylinder, and

(g) the first connecting rod is operatively connected to the piston-connecting means laterally outwardly of the cylinder.

3. An internal combustion engine as defined in claim 2, in which:

(h) the piston-connecting means is disposed at and extends laterally from the base of the piston and includes a wrist pin located laterally outwardly of the cylinder, and

(i) the connecting rod is oscillatively mounted to the wrist pin.

4. An internal combustion engine as defined in claim 2, in which:

(h) the piston-connecting means is narrow and moves between the crankarm during crankshaft rotation, the piston moving below the top of the crankshaft and at one side of the crankshaft.

'5. An internal combustion engine as defined in claim 2, in which:

(h) the piston-connecting means extends laterally out- (ward from the base of the piston, and

(i) the cylinder is provided with a lateral wall opening through which the piston-connecting means extends for connection to the connecting rod.

6. An internal combustion engine as defined in claim 5,

in which:

(j) the piston-connecting means includes a wrist pin located laterally outwardly of the cylinder, and

(k) the connecting rod is oscillatively mounted to the wrist pin.

7. An internal combustion engine, as defined in claim 6,

in which:

(l) the center axis of the wrist pin mounting the connecting rod is offset from, yet located substantially between 10 on either side of a line passed through the center axes of the crankshaft and crankarm bearing when the crankarm is in dead top center position.

8. An internal combustion engine as defined in claim 1,

in which:

(f) a second crankshaft includes -a crankarm having a crankarm bearing,

(g) the first and second crankshafts being disposed in laterally adjacent, spaced relation on opposite sides of the piston, and,

(h) a second connecting rod operatively connects the crankarm bearing of the second crankshaft to the piston-connecting means, the second connecting rod also having a length that is less than twice the length of the crankarm, yet greater than the crankarm length.

9. An internal combustion engine as defined in claim 8,

in which:

(i) the piston-connecting means extends laterally outward from opposite sides of the cylinder,

(j) the first connecting rod is connected to the pistonconnecting means at one side of the cylinder, and

(k) the second connecting rod is operatively connected to the piston-connecting means at the other side of the cylinder.

10. An internal combustion engine as defined in claim 9,

in which:

(1) the piston-connecting means extends laterally from the base of the piston and includes a pair of wrist pins, one at each side and outwardly of the cylinder,

(in) the first connecting rod is oscillatively mounted to one of the wrist pins, and

(n) the second connecting rod is oscillatively mounted to the other wrist pin.

11. An internal combustion engine as defined in claim 9,

in which:

(1) the cylinder is provided with opposed lateral wall openings through which the piston-connecting means is laterally extended and reciprocatively moved with the piston.

12. An internal combustion engine as defined in claim 11, in which:

(m) the piston-connecting means includes a pair of wirst pis, one at each side and outwardly of the cylinder,

(n) the first connecting rod is oscillatively mounted to one of the wrist pins, and

(o) the second connecting rod is oscillatively mounted to the other wrist pin.

13. An internal combustion engine as defined in claim 12, in whch:

(p) the piston-connecting means extends laterally from the base of the piston, and moves down between the crankarms during crankshaft rotation, and

(q) the connecting rods are located on opposite sides of the cylinder and above the bottom of the cylinder.

14. An internal combustion engine as denfied in claim 12, in which:

(p) the center axis of each wrist pin mounting its associated connecting rod is offset from, yet located substantially between 10 on either side of a line passed through the center axes of the associated crankshaft and crankarm bearing when the crankshaft is in dead top center position.

References Cited UNITED STATES PATENTS Scott 7444 Myers 7444 Canfield 7444 Bruegger 7444 Trammell 123--197 8 FOREIGN PATENTS US. Cl. X.R. 

